This invention relates generally to a multi-capacitor module and particularly, but not by way of limitation, to its use in a cardiac rhythm management system.
Capacitors are electrical components that store electrical energy in an electromagnetic field between electrodes that are separated by a dielectric insulator. Each electrode carries a charge that is opposite in polarity to the charge on the other electrode. Capacitors find many applications in a wide variety of electric circuits. For example, implantable defibrillators and pacemakers provide cardiac rhythm management therapy to the heart in the form of low energy pacing pulses to evoke heart contractions and high energy electrical countershocks to interrupt certain arrhythmias. Such cardiac rhythm management devices include circuits that sense heart activity and control the delivery of therapy. Many of these circuits use capacitors. For example, capacitors are used to store energy for the delivery of low or high energy therapy to the heart. Capacitors are also used to in filter circuits that remove unwanted signals. In another example, capacitors are used to store energy for stabilizing power supply circuits.
One goal in designing electronic devices is to reduce the size of the electronic device, which makes the device more portable. In implantable devices, size reduction is not just important, it is critical. A smaller device is easier for the physician to implant in the patient. Moreover, by reducing the size of other components in an implantable device, a larger battery can be used, prolonging the implanted longevity of the device before a replacement device is required. Increasing the implanted longevity of such devices reduces the cost of the patient""s medical treatment, which is extremely important in the present environment of rising medical costs.
Many discrete capacitors used in implantable medical devices are surface mount devices that are mounted onto multilayer hybrid substrate circuit boards. Unfortunately, such capacitors often consume a large area of the circuit board. This tends to increase the size of the implantable device, or alternatively, tends to reduce implantable longevity by reducing the battery size that can be accommodated in a particular size device. Thus, there is a critical need to more effectively use discrete capacitors in implantable medical devices and other electronic circuits.
The above-mentioned shortcomings, disadvantages and problems are addressed by the present invention, which will be understood by reading and studying the following specification and accompanying drawings that form a part thereof. The present invention provides, among other things, a multi-capacitor module. The module includes a module body having opposing top,and bottom module surfaces. The module body including electrical terminals for connecting to an external circuit. The module also includes a plurality of capacitors within the module. Each capacitor is electrically coupled to terminals on the module body. Each capacitor includes a capacitor body having opposing first and second capacitor ends defining a capacitor height therebetween. The first capacitor end is adjacent to the bottom module surface. The second capacitor end is adjacent to the bottom module surface. One of the first and second capacitor ends defines a length and a width of the capacitor. The capacitor height is longer than each of the length and the width of the capacitor.
In various further embodiments, the module includes capacitors having a first and second capacitor terminals at respective first and second capacitor ends. At least one conductor is electrically coupled to at least one of the second capacitor terminals (approximately adjacent to the top module surface). The conductor extends to the bottom surface of the module. Each capacitor includes a base extending between the first and second capacitor ends. The first capacitor terminal extends partially along the base proximal to the first capacitor end. The second capacitor terminal extends partially along the base proximal to the second capacitor end.
In various further embodiments, the capacitors are tantalum capacitors (e.g., surface mount tantalum capacitors). The bottom module surface is open for accessing an interior of the module body. The terminals on the module body are located on the bottom surface of the module. In one embodiment, the present invention includes a circuit board having the above-described module mounted thereupon. In one embodiment, the circuit board comprises a hybrid circuit board substrate that includes multiple conductive and insulating layers.
Another aspect of the invention provides, among other things, a multi-capacitor module. The module includes a module body having opposing top and bottom module surfaces. Surrounding side surfaces extend between the top and bottom module surfaces. The top, bottom, and side module surfaces define an interior portion of the module therebetween. The module body includes electrical terminals for connecting to an external circuit. A plurality of tantalum capacitors are within the module. Each capacitor includes a capacitor body having opposing first and second capacitor ends defining a capacitor height therebetween. One of the first and second capacitor ends defines a length and a width of the capacitor. The capacitor height is longer than each of the length and the width of the capacitor. The capacitors are vertically disposed in a row within the module. The first capacitor ends are substantially adjacent to the bottom module surface. The second capacitor ends are substantially adjacent to the top module surface. Each capacitor includes a base extending between the first and second capacitor ends. A first capacitor terminal is located at the first capacitor end. The first capacitor terminal extends partially along the base proximal to the first capacitor end. A second capacitor terminal is located at the second capacitor end. The second capacitor terminal extends partially along the base proximal to the second capacitor end. A conductor is located substantially in the interior portion of the module. The conductor extends along the interior portion of the top module surface. The conductor is electrically coupled to each of the second capacitor terminals. The conductor also extends along the interior portion of one of the side module surfaces, and further extends to the bottom module surface. The conductor provides an electrical terminal for connecting the second capacitor terminals to an external circuit.
In various further embodiments, the present invention also includes a circuit board having the above-described module mounted thereupon at the bottom module surface. The circuit board is electrically coupled to a portion of the conductor at the bottom module surface. The circuit board is also electrically coupled to the first capacitor terminals at the bottom module surface. In one embodiment, the circuit board comprises a hybrid circuit board substrate that includes multiple conductive and insulating layers. In a further embodiment, the conductor and the first capacitor terminals are soldered to the circuit board. In one embodiment, the module body includes a notched corner between the top module surface and one of the side module surfaces, and five capacitors are carried within the module.
Another aspect of the invention provides, among other things, a cardiac rhythm management system. The system includes a housing, a battery within the housing, and a hybrid circuit board substrate, within the housing, The substrate includes multiple conductive and insulating layers. A multi-capacitor module is mounted to the substrate. The multi-capacitor module includes a module body having opposing top and bottom module surfaces. The module body includes electrical terminals that are electrically coupled to the substrate. The bottom module surface is mounted to the substrate. A plurality of capacitors is carried within the module.
In various further embodiments, the capacitors are surface mount tantalum capacitors. Each capacitor is electrically coupled to terminals on the module body. Each capacitor includes a capacitor body having opposing first and second capacitor ends defining a capacitor height therebetween. One of the first and second capacitor ends defines a length and a width of the capacitor. The first capacitor end is approximately adjacent to the substrate. The capacitor height is longer than each of the length and the width of the capacitor. Each capacitor includes first and second capacitor terminals at the respective first and second capacitor ends. At least one conductor is electrically coupled to at least one of the second capacitor terminals. The conductor extends to the bottom surface of the module. The conductor provides one of the terminals, on the module body, that is electrically coupled to the substrate.
In various further embodiments, each capacitor includes a base extending between the first and second capacitor ends. The first capacitor terminal extends partially along the base proximal to the first capacitor end. The second capacitor terminal extends partially along the base proximal to the second capacitor end. In one embodiment, the bottom module surface advantageously occupies less mounting area on the surface of the substrate than areas of the bases summed over the plurality of the capacitors. In one embodiment, the first capacitor terminals provide terminals, on the module body, that are electrically coupled to the substrate. The bottom module surface is open for accessing an interior of the module body.
Another aspect of the invention provides, among other things, a method of forming a multi-capacitor module. A module body is formed to include opposing top and bottom module surfaces, and to include electrical terminals for connecting to an external circuit. A plurality of surface mount capacitors are disposed within the module. Each capacitor includes a capacitor body having opposing first and second capacitor ends defining a capacitor height therebetween. One of the first and second capacitor ends defining a length and a width of the capacitor. The capacitor height is longer than each of the length and the width of the capacitor.
Another aspect of the invention provides, among other things, a method of making a cardiac rhythm management system. A housing is formed. A battery is disposed within the housing. A hybrid circuit board substrate, including multiple conductive and insulating layers, is disposed within the housing. A multi-capacitor module is mounted on the substrate. The module includes a module body having opposing top and bottom module surfaces. A plurality of capacitors is disposed within the module. In a further embodiment, disposing the plurality of capacitors includes disposing a plurality of surface mount tantalum capacitors within the module.
Another aspect of the invention provides, among other things, a method of using a plurality of capacitors. Each capacitor includes opposing first and second capacitor ends defined by a capacitor length and a capacitor width. The capacitor includes a base defining a capacitor height that is longer than each of the capacitor length and width. The capacitors are inserted into a multi-capacitor module having opposing top and bottom module surfaces such that the first capacitor ends are approximately parallel and proximal to the bottom module surface. The bottom module surface is open (such as for allowing insertion of the capacitors). The bottom module surface is mounted to a hybrid circuit board substrate.
In various further embodiments, the method includes electrically coupling a terminal on each second capacitor end to the substrate, such as by contacting the terminal on at least one of the second capacitor ends using a conductor and attaching the conductor to the substrate. In one embodiment, attaching the conductor to the substrate includes soldering the conductor to the substrate. A terminal on each first capacitor end is electrically coupled to the substrate. In one embodiment, electrically coupling the terminals on each first capacitor end to the substrate includes soldering the terminals on each first capacitor end to the substrate.
Another aspect of the invention provides, among other things, a method of mounting surface mount capacitors on a circuit board. Each capacitor includes a solid rectangular shape that includes a base having electrical contacts at opposing ends of the base. A plurality of the capacitors are inserted vertically into a module having opposing top and bottom module surfaces. The module includes side module surfaces extending between the top and bottom module surfaces. The capacitors are inserted such that the base of the capacitor is parallel to one of the side module surfaces. The electrical contacts at opposing ends of the base of the capacitor are proximal to the respective top and bottom module surfaces. The electrical contacts that are proximal to the bottom module surface are electrically coupled to the board. The electrical contacts that are proximal to the top module surface are electrically coupled to the board via a conductor extending therebetween.
In summary, the present invention provides, among other things, a multi-capacitor module for carrying vertically-oriented surface mount capacitors. The module provides at least one conductor for coupling to the substrate capacitor terminals that are distal thereto. The module occupies less space, when mounted to a circuit board substrate, than individually mounting the bases of the surface mount capacitors to the substrate. This allows more efficient use of volume within an implantable cardiac rhythm management device, reducing its size, or alternatively, increasing its implanted longevity. Other advantages will become apparent upon reading the following detailed description of the invention and viewing the accompanying drawings that form a part thereof.